Question

A light ray originating from water strikes on water-air interface with an angle of incidence 49 degree .The angle of refraction on air medium is??

Answer 1

Speed of the light in air = 3 × 10⁸ m/s.

Speed of the light in Water = 2.25 × 10⁸ m/s.

∴ Refractive Index of air with respect to water = 2.25 × 10⁸/3 × 10⁸

= 2.25 /3

= 0.75

Now, Using the Formula,

Refractive Index of air w.r.t water = Sin i/Sin r

⇒ 0.75 = Sin 49°/Sin r

⇒ Sin r = Sin 49/0.75

⇒ Sin r = 0.75°/0.75 [Sin 49° is 0.75]

∴ Sin r = 1

⇒ Sin r = Sin 90

On Comparison,

r = 90°

Hope it helps.